The estimation of power quality (PQ) indices has a vital importance on the development of national PQ standards not only because provides truthful information about PQ conditions in our facilities, but also because permits to establish, with an own criterion, the values for the limits of the most common PQ disturbances. This paper proposes a methodology for the estimation of PQ indices based on statistical sampling and weighting factors techniques which are applied for commercial and industrial customers in the city of Bogota. In addition, some strategies for the classification of the type of customer as well as some final obtained values of PQ indices in Bogota are presented.